IBooks lost forever. Customer service very nice but flailing

My four-year-old iPad died in Witchita: screen went dark. Still rechargable, still making sounds when using the passcode. Took it to the Apple store in Kansas City on the Plaza. Genius bar advised not spending any money to repair, rather simply buy a newer iPad. Took their advice. However: of the 42 iBook purchases on the old iPad only 38 were available to download on the new iPad. The four missing skus were collections (16 novels by P.D. James, 33 by Ngaio Marsh, 11 by Ian Fleming, 6 by Patricia Wentworth). Phoned Apple customer service and all were very pleasant and professional, but none could answer the basic question: why wouldn't iBooks stored in the Cloud be available to be accessed to a new device? Of the four missing skus all were multi-book sets or collections that were sold at an attractive sale price, which is frustrating as they are no longer sold (at that price, or as a set) on the platform. Part of me thinks that if I spent $200 now to have my old iPad fixed I would have access to them again. I posited this question to each agent, and all I really received were well-meaning crickets. I asked if the question could be sent higher up the chain. No. And there was no offer to give a credit for the well-documented purchases. This all explains why I had 42 iBook purchases and I have 227 Kindle purchases. Even though Amazon is pretty evil, at least they make their app available over multiple platforms. And they have yet to take purchased books away. Color me very disappointed in Apple.